Electric switch



Patented Nov. 17, l953 Y ELECTRIC SWITCH Raymond H. Boardman, Hartford,Conn., as-

signor to The Hart Manufacturing Company, Hartford, Conn., a corporationof Connecticut Application February 21,1950, Serial No. 145,359

`the casing is then secured tothe casing by any conventional means suchas a plurality of screws which are threaded into the casing to hold thecover assembled to the casing. Such assembly by screws, for example,requires manual operations which are time-consuming and thereforecostly.

Also, the switch operating means is generally actuated by a knob orhandle which is easily de- `tachable from a stem projecting from theoperating member, and friction means in the form of a spring orotherwise are usually employed to detachably retain the knob on rsaidoperating stem. In some constructions presently in use, the spring issomewhat loosely supported by the stem or stem-receiving recess in theknob and, when the knob is removed from the stem, the spring isdislodged from its operative position and has to be replaced when theknob is restored to operative position upon the operating stem.

It is an object of the present invention to facilitate the securing of acover to the open side of` a switch casing by meansrequiring a minimumamount of manual operation, the locking of the cover to the casing beingperformed by the simple insertion of a single locking member requiringno threaded attachment. i

It is another object of the invention to modify the switch casingwithout increasing the cost thereof so as to accommodate the lockingmeans `and facilitate the attachment thereof to the parts engagedthereby.

It is a further object of the invention to provide friction meansforholding a manually operable knob to the stem of a switch actuatingmeans, the friction means being maintained in operative position on saidstem without possi- 3 Claims. (Cl. 20G-168) In the drawing:

Figure l is a perspective view of an exemplary electric switch embodyingthe principles of the present invention.

Fig. 2 is a side elevation of the switch shown in Fig. 1, the casing ofsaid switch being partly ltaroken away to illustrate details of theinvenion.

Fig. 3 is an exploded perspective view illustrating components of theelectric switch shown in Fig. l.

Fig. 4 is a sectional view of a subassembly of some of the components ofthe switch shown in the other gures and shown on a larger scale than insaid figures.

The exemplary switch embodying the present invention comprises a casingI0 which may be suitably molded/to the desired shape from any suitablematerial such as, for example, a moldable phenolic resin resistant tothe temperatures generated by the arcing of contacts contained in bilityof detachment therefrom during the connection of the knob to the stem orseparation of the knob therefrom.

Details of these objects andA of the invention as Well as other objectsthereof are set forth in the following specification and illustrated inthe `accompanying drawing comprising a part therethe casing. In thecasing illustrated herein, one wall has been formed open such as the topI2, and a bottom I4is molded integrally with the side walls of thecasing. Extending transversely across the bottom and formed during themolding of the casing is a channel I6 having a` convex bottom wall orsurface I8. The sides 2!! and 22 are also provided with molded channelsor flat grooves 24 extending from the open top I2 to the bottom I4, saidgrooves 24 being parallel to each other and merging at one end with thechannel I6 in the bottom I4, as is clearly evident from Fig. 3.

The specic arrangement of switching arms and contacts carried thereby isnot of the essence of the present invention and is therefore illustratedonly in a general way in Fig. 3. It is considered sufficient to statethat the casing I0 contains a plurality of switch arms 26 and 28 whichhave contacts thereon engageable'with fixed con- Atacts supported withinthe casing but not illustrated in detail in Fig.` 3. The various armsand contacts are connected with suitableterminal screws 30 and 32 bywhich circuit wires or conduits are connected to the switch.

Centrally of the bottom of the casing'is a bearing aperture 34 which.rotatably supports one end 36 formed on switch operating member 38 whichmay, for example, be molded from material similar to that from which thecasing I0 is formed.

Projecting oppositely to the end 36 on member 38 is an operatingy stem40 by which the operating member 38 is rotated about its axis relativeto casing I0 so as to cause various cams formed on member 38 to actuatethe various switch arms such as 26 and 28. The operating member 88 isalso provided with an integral boss 42 having a recess 44 extendingthereinto from the outer end thereof in a direction parallel to the axisof the stem 45. The stem A4I) is also preferably provided with at leastone longitudinal groove 46 for purposes to be described.

A cover 48 which is preferably formed from suitable sheet metal, but maybe formed from any other suitable non-metallic material, if desired, isprovided for purposes of closing the open top I2 of the casing I0. Ifdesired, the rim of the open top I2 may be provided with a, marginalrecess 58 extending around the inner perimeter thereof for purposes ofreceiving the cover 48, whereby the outer surface of the cover may beilush with the top edges of the sides of the casing.

Connected at one end to opposite edges of cover 48 and extendingtransversely thereto are a pair of preferably slightly exible,substantially parallel arms 52. In actual practice, when the cover 48and arms 52 are out of contact with casing I0, it is preferred that the.free ends of the arms 52 extend slightly closer to each other than theends thereof connected to the cover, whereby the free ends of the arms52 will snugly engage the bo*- tom surfaces of the grooves 24 within thesides of the casing and within which grooves said arms are disposed whenthe cover is mounted in operative position to close open top I2 of thecasing.

Extending centrally from the cover 48 is a threaded boss 54 whichextends outward from the cover in an opposite direction from the arms52.

Said boss may be used for securing the switch to a suitable supportingpanel, not shown, by being disposed through a hole therein and having asecuring nut threaded to the boss 52 to clamp the switch to the panel.When the cover 48 is assembled so as to close the open top I2 of thecasing, the inner surface of the cover 48 engages the outer end of boss42 on operating member 38 so as to hold said operating member in itsoperative position within the casing. The operating stern 40 projectsthrough and is rotatably supported within the central aperture of boss54, whereby the operating member 38 is supported at its opposite ends byboss 54 and bearing aperture 34 within the casing Ii). If desired, thecover 48 may also be used to retain in operative position within thecasing I8 various panels, strips, or

other positioning members, not shown, positioned between the innersurface of cover 48 and the various contacts and switch arms supportedwithin the casing in accordance with common practice.

4The cover 48 is secured in operative position over the open top I2 ofthe casing by means of a locking member 56 which extends transverselyacross the casing into engagement with the arms 52 which are disposedwithin the grooves 24 `of the casing. The locking member 56 ispreferably formed from flexible material such as a strip of springsteel, and the ends 58 thereof are bent at an angle thereto as shown inFigs. l through 3. The free ends of the arms 52 are provided withopenings or slots 60 of suicient width and length to permit the lockingmembers 56 and the bent ends 58 thereof to be inserted through saidslots while the member 56 extends transversely to the planes of the arms52.

When the cover is assembled in operative position as described aboverelative to the casing I0, the slots 60 will be disposed adjacent theends of channel I6 in the bottom I4 of the casing. The

assembled casing and cover may be supported 75 within a suitable Jig orfixture to hold them in assembled relationship, said jig or-ilxturebeing provided with openings or spaces adequate to permit, for example,insertion of one end 58 of the locking member 56 through the aperture 60in one of the arms 52 from the exterior thereof, and

then permit the locking member 56 to be slidably moved along channel I6until the leading bent end 58 can be moved through the slot 60 in theother arm 52. Such insertion of the other end 58 can be made afterlocking member 56 is fiexed a certain extent due to the intermediateportion of the locking member engaging the intermediate portion of theconvex bottom I8 of channel I6 as illustrated in Fig. 2.

Following the insertion of said end 58 of the locking member through theslots 60 of the second arm 52, the resilience of the locking member 56will cause the ends 58 thereof to snap a slight distance longitudinallyof the arms 52 so that the ends 58 engage the outer surface of the arms52 adjacent the slots 68 and prevent accidentalmovement of the lockingmember from the slots and arms. While there will be a slight spacebetween the outer ends of locking member 56 and the end portions of thebottom of channel I8 when the member 56 is in locking position, theintermediate portions of the locking member and channel will be in rmengagement and the intermediate portion of the locking member willbeiiexed. The strength of the locking member 5611s also such as toprevent appreciable movement of the arms 52 and cover 48 relative to thecasing II) and the connection therebetween is also enhanced by thefrlctional engagement of the outer ends of arms52 with the bottomsurfaces of grooves 24 in the sides of the casing.

A manually operable knob 62, which may be formed by molding fromsynthetic resin or any other suitable material, is provided with astemreceiving recess 64. Said recess 64 may contain a suitable rib 66 orany other suitable means for interengaging with one of the grooves 45 instem so as to prevent relative rotation between the stem and knob.Preferably, the knob also contains a cavity 68 extending inward from itsinner surface for purposes of accommodating the threaded boss 54. Theknob 62 is movable longitudinally of the stem 40, but means are providedfor frictonally retaining the knob in operative position upon the stem.Said means comprise a spring 'I0 having an end 'I2 which is slightlycurved longitudinally so as better to engage with greater friction thewalls of the recess 64 in the knob 62. When the knob is removed from theend 12, said end will be spaced away from the stem as clearly shown inFig. 3 and also, in dotted lines. in Fig. 4. When compressed intofrictional engagement with the walls of cavity 68 of the knob, thespring end 12 will be at least partially disposed within one of thegrooves in stem 40.

The other end of the spring 'I0 is bent upon itself to form acompressible loop 14, the sides of which loop frictonally engage theopposite walls of the recess 44 formed in boss 42 of the switchoperating member 38. Such frictional engagement ofthe loop 14 with therecess 44 will retain the spring operatively assembled with theoperating member 38 prior to the attachment of the knob 62 to stem 40.

Intermediate the ends of the spring, the spring is bent to provide alaterally extending portion 'I6 which overlies the inner surface ofcover 48 as clearly shown in Fig. 4. Thus, when the cover 48 has beenassembled with casing I0 so as to hold the operating member 38 inoperative position within the casing, the lateral portion 'I6 of spring'I0 will engage or be only slightly spaced from the inner surface ofcover 48 and thereby prevent outward movement of the spring relative tothe stem lli). Thus, when knob 62 is being secured to or removed fromstem ll the lateral portion 16 of the spring will prevent outwardseparative movement of the spring from the stem by engaging the cover48, and the abutment of the innermost end of loop 16 of the spring withthe bottom of recess 44 will prevent inward movement of the springrelative to the stem 49 as when the knob is being attached to stem 40.Thus, the knob 62 may readily be mounted upon the stem or withdrawntherefrom while spring I0 is prevented from separating from the stem 49.

It will be seen'from the foregoing that the pres ent invention providesan extremely simple, d'urable and inexpensive means for maintaining acover detachably secured to a switch casing and the assembly of theattaching means may be performed quickly and inexpensively With aminimum requirement of manual operations. Inclusion of such securingmeans within the switch isaccomplished by slightly modifying the Switchcasing, but such modication adds no expense to the production thereof. Asubstantial overall saving is thus possible when using the presentinvention to secure the cover to the switch casing, said cover when sosecured also serving to ,retain in assembled, operative position thevarious movable contacts and switch arms embodied within the casing.

The retaining spring by which the operating knob is removably secured tothe stem of the operating member of the switch is also inexpensive toproduce and provides means for retaining the spring assembled with theoperating stem and permits the attachment of the conventional knob tosaid stem or removal of the knob therefrom without dislodging thefriction spring from its operative position on the stem.

While the invention has been illustrated and described in its preferredembodiment and has included certain details, it should be understoodthat the invention is not to be limited to the precise details hereinillustrated and ldescribed since the same may be carried out in otherways, falling within the scope of the invention as claimed.

I claim as my invention:

1. An electric switch casing having a bottom provided with a convexsurface portion and an open top, a removable cover for said open top. a-

pair of substantially parallel arms connected at one end to oppositeedges of said cover and extending along opposite sides of said casing tosaid bottom, the free ends of said arms having openings therein disposedupwardly relative to the lower-most region of said convex surfaceportion, and locking means comprising a removable spring member iiexedinto engagement with said convex surface portion of said bottom and.extending across said bottom between said legs and disposed at its endswithin said openings in said legs to secure said cover to said casing.

2. An electric switch casing having an open top and a bottom providedwith a channel extending across the exterior surface thereof betweenopposite sides of said casing, the bottom surface of said channel beingconvexly curved longitudinally, a removable cover for said open top, apair of arms connected at one end to opposite edges of said cover andextending along opposite sides of said casing to said bottom, the 'freeends of said arms having slots therein, and a locking means comprising aspring strip bent at its ends to provide locking hooks and flexed intoengagement with the intermediate portion of the convex bottom of saidchannel, said strip extending between said arms transversely to theplanes thereof and the ends of said strip extending through said slotsin said arms detachably to secure said cover to said casing, the bentends of said spring strip being movable through said slots duringassembly and engageable with the exterior surfaces of said arms toprevent accidental separation of the ends of said strip from said arms.y

3. An electric switch casing having an open top and a bottom providedwith a channel extending across the exterior surface thereof betweenopposite sides of the casing, a removable cover for said open top havinga pair of arms depending from opposite edges thereof and extending alongthe opposite sides of the casing to said bottom, the free ends of saidarms having slots therein disposed at opposite ends of said channel, anda removable spring strip having hook means at its ends engageable withsaid arms through said slots with the intermediate portion of said stripdisposed within said vchannel and engaging the bottom of the casingtosecure said cover to the casing. 4

RAYMOND H. BOARDMAN.

References Cited in the sie of this patent UNITED STATES PATENTS NumberName Date 1,228,028 Klein May 29, 191'? 1,451,146 Fate Apr. 10, 19231,682,849 Morey Sept. 4, 1928 1,757,814 Quiggin et al May 6, 19302,254,729 Bryant Sept. 2, 1941 2,301,169 Engstrom Nov. 3, 1942 2,345,685Rhein Apr. 4, 1944 2,361,559 Mekelburg Oct. 31, 1944 2,368,679 Popp Feb.6, 1945 v

